The present invention relates generally to the field of window coverings, and more particularly, to a light-control window covering and a method and apparatus for its manufacture.
Light-control window coverings typically include a front and rear portion made from a sheer material and a plurality of opaque vanes extending between the sheer materials. The light-control covering is movable from an open, light-passing position in which the vanes are horizontal, to a light-blocking position in which the vanes are substantially vertical. The prior art light-control window coverings and the apparatus and method for the manufacture of the light-control coverings have a number of problems and shortcomings. One problem with these light-control products is the lack of strength of the connection between the vanes and the sheer materials. Additionally, the appearance of the connection between the vanes and the sheer materials may be uneven or may not adequately match the color or pattern of the vanes and/or sheer material. Further, the profile of the vanes of some of these light-control products does not maximize the viewable area when the light-control window covering is in the light-passing position. Additionally, the apparatus and method for manufacturing the light-control window coverings are slow and require that only a portion of the light-control product be assembled at a time.
Numerous methods have been developed to form light-control window coverings. U.S. Pat. Nos. 3,384,519 and 3,661,665 to Froget disclose a method of welding the marginal edges of a plurality of vanes to two layers of material. First, each vane is welded to one face of the first layer of material. As each vane is welded to the first layer of material, the first layer and the welded vane are wound onto a reel. After all of the vanes have been welded to the first layer of material and wound onto a reel, the combination is then unwound such that the free edge of each vane comes into contact with a second layer of material. The free edge is then welded to the second layer of material. In this manner a light-control window covering is formed with one face of the vane being welded at its marginal edge to the first layer and the second face of the vane being welded at its second marginal edge to the second layer.
U.S. Pat. No. 5,313,999 to Colson et al. describes a method and apparatus for forming a light-control window covering in which one side of individual vanes are attached with adhesive to a first continuous sheet of material and the other side of the vanes are then attached with adhesive to a second continuous sheet of material. The first and second sides of each vane are attached to the first and second sheets one at a time. Colson et al. argued that the Froget window covering had a number of undesirable features, including an xe2x80x9cuneven outer appearancexe2x80x9d; xe2x80x9cproducing unwanted crimps and creases in the material, which can result in fatigue failurexe2x80x9d; that the process is a xe2x80x9crelatively slow processxe2x80x9d; xe2x80x9cthat heat welds are limited in strengthxe2x80x9d; and xe2x80x9cthe difficulty in achieving uniformly straight heat welded joints over an extended length.xe2x80x9d (See col. 1 line 66-col. 2 line 17).
However, the solutions proposed by Colson et al. also have a number of drawbacks. First, the adhesive that is used to provide the bond between the vanes and the sheer materials is applied to one vane at a time, making the manufacturing process relatively slow. Additionally, the adhesive requires special additives to reduce yellowing and discoloration of the adhesive as well as subsequent processing of the bond to xe2x80x9croughenxe2x80x9d the glue to provide a dull appearance. Another problem with the Colson et al. window covering is the bias of the vanes toward the light-blocking position. This bias requires additional force to move the vanes to the light-passing position and to maintain them in that position. Further, one embodiment of the light-control window covering of Colson et al. requires that the vanes do not have a crease but rather have smoothly curving portions (see col. 16 lines 25-30) and therefore do not allow for a straighter appearance of the vane. This feature reduces the viewable area when the light-control window covering is in the light-passing position. Colson et al. does disclose a second embodiment with a bend that is formed by scoring the vane material. Scoring the vane material, unlike perforating, creates a line of weakness that could result in failure of the light-control covering.
U.S. Pat. No. 5,228,936 to Goodhue, describes a method and apparatus for forming a light-control window covering, in which all of the vanes are attached with adhesive to the first and second sheets simultaneously. As in Froget and Colson, one side of each vane is attached to a first sheet and the other side of each vane is attached to a second sheet. Since the vanes are applied to the first and second sheets side by side, the vanes do not overlap when the window covering is in the light-blocking position. As a result, light is likely to pass through the spaces between adjacent vanes in the closed.
U.S. Pat. No. 5,888,639 to Green et al. discloses a method and apparatus for forming a light-control window covering formed by continuously welding three substrates of material together to form a three-substrate web having first and second light-control regions and a center vane or opaque region located there between. Portions of the three-substrate web are laterally offset from one another and are adhesively attached to form a light-control window covering. While this process increases the speed of manufacture of the light-control product, it still requires both an adhesive and welding operation. Additionally, it precludes the use of a single continuous sheet of sheer material for the light-control window covering.
U.S. Pat. Nos. 5,846,360; 5,885,409; and 5,891,208, to Gilldisclose a method and apparatus for manufacturing a multilayer filter by attaching first and second filter layers to a plurality of ribbons utilizing ultrasonic welding equipment.
It would be desirable to form a light-control window covering in which all of the vanes are simultaneously attached to the first and second sheets where the vanes of the resultant light-control window covering overlap one another in the light-blocking position. It would also be desirable to form a light-control window covering without the need for an adhesive bond resulting further in the need for adding materials to the adhesive to reduce yellowing, or processing of the bond to dull the adhesive bond. It would also be desirable to form a light-control window covering that had an increased viewable area when the light-control window covering is in the light-passing position. It would be further desirable to form a light-control window covering with a strong bond without the need for adhesive. It would also be desirable to form a light-control window covering in which at least one of the attachment areas between the vane and the sheer material is hidden by a portion of the vane, when the light-control window covering is in the light-passing position. It would also be desirable to form a light-control window covering with all of the benefits noted above.
Accordingly, an embodiment of the invention is a light-control window covering where all of the vanes are simultaneously attached to the first and second sheets. The vanes of the resultant light-control window covering overlap one another in the closed or light-blocking position.
Another feature of the light-control window covering includes ultrasonic welds between the vanes and the sheer material without the need for an adhesive bond. The ultrasonic weld does not yellow, and/or does not have a gloss appearance, and/or blends in with the sheer materials and the vanes, and/or has its own pattern.
A further feature of the light-control window is that each vane includes a crease to provide a greater viewing area when the light-control window covering is in the light-passing position.
Another feature of the light-control window covering is that a ribbon of thermoplastic material is attached to the first and/or second sheer material to increase the strength of the welds between the vane and the sheer material.
In another embodiment of the light-control window covering, a ribbon is attached to the sheer material and masks the appearance of the weld of the vanes and sheer material.
One embodiment relates to a light-control window covering comprising a first sheer material, and a second sheer material. A plurality of vanes having perforations are operatively connected to the first and second sheer materials. Each vane bends proximate the perforations as the first and second sheer materials are moved relative to one another.
A further embodiment includes a light-control window covering including a first sheer material, and a second sheer material spaced apart from the first sheer material. Each sheer material has a first face and a second face. A plurality of vanes have a first and a second longitudinal margin adjacent a first face of the first and second sheet of sheer materials respectively. A plurality of ribbons are adjacent the second face of at least one of the first and second sheets of sheer material. Each ribbon is ultrasonically welded to one of the first and second sheer materials and to a respective longitudinal margin of the vane.
Another embodiment includes a method for manufacturing the light-control window covering comprising feeding a first and a second sheet of sheer material spaced apart from and parallel to one another. Each sheet of sheer material has a first side and a second side. A plurality of strips of vane material are provided, each strip of vane material having a pair of longitudinal edges and a predetermined width as measured between the longitudinal edges, a center region, a first side and a second side, and first and second longitudinal margins. A plurality of spaced apart ribbons are provided proximate the second side of a respective first and second sheet of sheer material. Each strip of vane material is separated from an adjacent strip of vane material by a predetermined distance that is less than the predetermined width of the strip of vane material. The strips of vane material are attached to the first side of the sheet of sheer material along the first longitudinal margin. The strips of vane material are attached to the second sheet of sheer material along the second longitudinal margin. The plurality of spaced apart ribbons are attached to at least one of the sheets of sheer material and to the vanes.
Still another embodiment includes an apparatus for manufacturing a light-control window covering having a first sheet of sheer material, a second sheet of sheer material, a plurality of vanes and a plurality of ribbons. The apparatus includes a perforating station for perforating the vanes and a plurality of spaced apart folders for folding the longitudinal margins of the vanes. A plurality of first ultrasonic welders weld a first longitudinal margin of each vane to the first sheet of sheer material and to a respective ribbon. A plurality of second ultrasonic welders weld a second longitudinal margin of each vane to the second sheet of sheer material and to a respective ribbon. The apparatus also includes a plurality of rotary anvils located between the first and second sheets of sheer material for attaching each respective vane to the second sheet of sheer material and to each respective ribbon.
These and other features of the present invention will be apparent upon consideration of the following detailed description of preferred embodiments thereof, presented in connection with the following drawings in which like reference numerals identify like elements throughout. All of the features discussed herein may be combined with any other feature or combination of features whether or not the combination is specifically recited.